AIT Pipefitter Level 3 Practice Test 2025 - Free Pipefitter Practice Questions and Study Guide

When connecting two or more boilers, the use of a stop/check valve is essential. This type of valve serves dual purposes: it can prevent backflow in the system, ensuring that water or steam doesn’t flow back into the boiler, and it can stop the flow of water or steam to one of the boilers during maintenance or repairs.

The stop/check valve's capability to isolate a section of the system is crucial because it allows for safe and convenient maintenance without having to shut down the entire system. Maintaining safety and operational integrity in boiler systems is critical, and a stop/check valve effectively addresses these needs.

Other valve types, while useful in certain situations, do not provide the same level of functionality needed when connecting multiple boilers. Ball valves, for example, are primarily used for on/off service but lack the backflow prevention feature. Relief valves are designed for pressure release to prevent overpressure conditions but do not control flow direction. Flow control valves manage the rate of flow but again don’t offer the backflow prevention necessary in this scenario.